1. Technical Field
Embodiments of the disclosure relate to systems and methods used to translate information between computer three dimensional variation models and geometric dimensioning and tolerancing (GD&T) callouts.
2. Description of the Related Art
There have been longstanding issues regarding how to effectively translate variation information between three dimensional (3D) variation analysis simulation tools and Geometric Dimensioning & Tolerancing (GD&T) callouts used to define allowable variation on drawings and in datasets for product definition.
The American Society Of Mechanical Engineers (ASME) Standard ASME Y14.5M GD&T is the industry standard product definition language that engineers use to establish allowable deviations from nominal. This language is predominantly a geometric requirements language. GD&T is one of the methods to describe the process capabilities used to refine variations analysis for a more accurate representation of variation. However, GD&T is not the only method.
Analysts can be very clever in developing an accurate characterization of variation that goes beyond the descriptions GD&T covers. However, in the end it is necessary to use GD&T to communicate the allowable variation of components and assemblies as established through analysis. In addition, analysts need to translate GD&T into variation models in 3D variation analysis tools in order to perform 3D variation analysis.
3D variation analysis simulations are computer simulations that predict the final state deviations of assembled components based on the components allowable variation and the proposed build indexing and sequencing of the components. The components allowable variation is defined as a range and distribution type and is a user defined input to the simulation software. The output of the software is also a variation range and distribution type for a measured value.
A variation analyst needs to translate GD&T into the 3D variation analysis tool in order to perform the 3D variation analysis. If the component's GD&T is undefined at the time the analysis is created, the analyst determines the allowable variation with the analysis software. This allowable variation must then be translated into a GD&T callout to be applied to the component. Since the way the 3D variation analysis tools represent variation is different from how variation is described using GD&T, there is a need to develop a generic method to translate GD&T specifications into the analysis software and vice versa.
Inconsistent and creative translations have resulted in analyses that either over constrain component tolerances, thus increasing component costs, or under constrain component tolerances which then drive costs into the assembly process. These are recurring costs that continue until a new analysis is performed with accurate translations.
The unique characteristic of this problem is the fundamental difference that exists between the languages used in GD&T and 3D variation analysis. The language used in the variation analysis process is a set of equations used either singularly or in combinations to simulate actual production variation. GD&T defines the limits or boundaries of allowable variation and depending on the geometry and applied symbology there is almost an infinite number of boundary situations. The inherent differences of the two languages require a rigorous set of standardized rules to ensure accurate translations are made between the two languages.
Some software vendor help files describe general relationships between simulated variation and GD&T but do not provide the level of detail required for consistent translation. Thus, analysts usually rely on their experience and intuition to perform ad-hoc translations. However, translations based on analysts' experience may not be consistent and typically can not be reliably validated.
Accordingly, there is a need for systems and methods that can translate variation information between computer 3D variation models and GD&T.